#include <bits/stdc++.h>
using namespace std;
const int N = 3e5 + 5;
int n,a[N];
long long sum[N];
inline void work() {
	cin >> n;
	for(int i = 1;i <= n;i++) cin >> a[i],sum[i] = sum[i - 1] + a[i];
	int pos = 1;
	while(pos < n && a[pos] > a[pos + 1]) ++pos;
	double lef = 0,rig = 1e9;
	for(int _ = 1;_ <= 60;_++) {
		double mid = (lef + rig) / 2;
		double mn = 1e9,mx = -1e9;
		for(int i = 1;i < pos;i++) mn = min(mn,sum[i - 1] - mid * (i - 1));
		for(int i = pos + 1;i <= n;i++) mx = max(mx,sum[i] - mid * i);
		if(mx >= mn) lef = mid; else rig = mid;
	}	
	printf("%.10lf\n",lef);
	// double ans = 0;
	// for(int i = 1;i <= n;i++)
	// 	ans = max(ans,max(sum[i],sum[n] - sum[n - i]) * 1.0 / i);
	// cout << ans << endl;
}
int main() {
	int T;
	cin >> T;
	while(T--) work();
	return 0;
}